AI agents call lean_minimal_hypotheses to retrieve information from Lean LSP MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool appears to retrieve or query minimal hypotheses related to Lean proof goals, consistent with the server's stated purpose of 'accessing' goal states and diagnostics. No evidence of modification, deletion, or execution. Absence of description reduces confidence, but sibling tools on this server are predominantly Read operations (diagnostics, outlines, documentation lookups).
From the tool's definition Tool name 'lean_minimal_hypotheses' suggests retrieval of hypothesis information from Lean project analysis.
Documented attack patterns abuse exactly the kind of access lean_minimal_hypotheses gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Lean LSP MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for lean_minimal_hypotheses:
{
"version": "1",
"default": "deny",
"tools": {
"lean_minimal_hypotheses": {}
}
}lean_minimal_hypotheses is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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lean_minimal_hypotheses. It is categorised as a Read tool in the Lean LSP MCP MCP Server, which means it retrieves data without modifying state.
Register the Lean LSP MCP server in PolicyLayer and add a rule for lean_minimal_hypotheses: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Lean LSP MCP. Nothing to install.
lean_minimal_hypotheses is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the lean_minimal_hypotheses rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for lean_minimal_hypotheses. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
lean_minimal_hypotheses is provided by the Lean LSP MCP server (ooo0ooo/lean-lsp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 23 Lean LSP MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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23 Lean LSP MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.